This assumption may be particularly important when one considers highly differentiated cells such as spermatozoa. In mature spermatozoa, the nucleus plays only a marginal, if any, role in modulation of their function, chromatin being condensed and little or no protein synthesis occurring during the life of mature spermatozoa. In these conditions, a nuclear translocation of ERKs seems unlikely. asthma inhalers
A similar situation can be found in platelets, where activation of ERKs occurs in response to stimuli that induce aggregation, such as thrombin. In contrast, in view of the fundamental role played by the equatorial segment in sperm-oocyte interaction, translocation of ERKs at this level may be expected. Following stimulation of the acrosome reaction, a conformational rearrangement of some proteins at the level of the equatorial segment has been demonstrated. These proteins appear to play an important role in sperm-oocyte fusion. Thus, the presence of ERKs at the level of the equatorial segment after the acrosome reaction might be related to the regulation and/or activation of proteins that mediate binding and fusion between sperm and egg plasma membranes. This process involves interaction between a complex of sperm surface antigens and integrins present on the egg surface (for review, see ).